Traditionally, brewer's wort, which is eventually fermented with yeast to produce beer beverages, was prepared by mashing a malted cereal, such as malted barley. This mashing process consisted primarily of heating an aqueous mixture of malted cereal until the enzyme activity of the malted cereal liquefied and saccharified the starch of the cereal to form fermentable sugars. Generally, the mashing temperature never exceeded 80.degree. C. since the enzyme activity of the malt is destroyed at temperatures above about 80.degree. C. The starch digesting enzymes contained in malted cereal are most active at temperatures of about 60.degree.-72.degree. C.
As the brewing art has progressed, there has been a desire to replace a significant amount of the malted cereal with unmalted cereals, such as corn, rice or barley. The prior art processes generally employed two processing stages. In the first cooker stage, the unmalted cereals are liquefied by treatment with appropriate enzymes at relatively low temperatures followed by heating to about 100.degree. C. in order to complete the starch degradation. The resulting liquefied starch is then mixed with malted cereals for subsequent enzymatic saccharification during the mashing stage. U.S. Pat. No. 2,790,718 is typical of such prior art. Other references of processes for preparing brewer's wort employing unmalted cereals and enzymes other than malted barley are U.S. Pat. Nos. 2,951,762; 3,081,172; 3,295,987; 3,353,960 and Canadian Pat. No. 945,920. Use of thermostable enzymes for the production of wort or liquefied starch is disclosed in U.S. Pat. Nos. 3,551,293 and 3,912,590 and British Pat. No. 1,345,413. All of these prior art processes either do not provide a commercially acceptable end product or they involve an undesirable step of heating the starch or mash to boiling. This can lead to undesirable flavors in the final product.
There is a need in the art for a process to produce brewer's wort which uses elevated temperatures for rapid and complete liquefaction of the cereals but does not require temperatures as high as 100.degree. C. and which does not require separate cooker and mashing equipment and procedures.